Babies can be born with herpes, a condition called neonatal herpes simplex virus (HSV) infection. This infection develops in an infant during the first six weeks of life and is caused by the herpes simplex virus, the same virus that causes cold sores and genital herpes in adults. While relatively rare, affecting approximately one in every 3,200 deliveries, neonatal herpes is serious due to the newborn’s underdeveloped immune system. Prompt recognition and treatment are paramount to minimizing severe complications.
How Neonatal Herpes is Contracted
The vast majority of neonatal HSV infections (over 85% of cases) occur during labor and delivery as the infant passes through the birth canal. This transmission route, known as perinatal acquisition, exposes the baby to the virus present in the mother’s genital tract, often from asymptomatic shedding or active lesions. Transmission risk is much higher when the mother acquires a primary HSV infection late in pregnancy, especially within the last six weeks before delivery. In this scenario, the mother has not yet developed and passed protective neutralizing antibodies across the placenta, leaving the baby highly vulnerable.
A recurrent maternal infection carries a transmission risk of less than 3% because the mother’s established immune response provides the infant with passive antibody protection. Less common routes include in utero acquisition (about 5% of cases), where the virus crosses the placenta and can lead to congenital effects. Postnatal acquisition (the remaining 10%) happens after birth, typically from contact with someone, such as family members or hospital staff, who has an active HSV-1 lesion like a cold sore.
Recognizing Symptoms and Understanding Severity
Neonatal herpes is categorized into three main classifications based on the extent of the infection, generally manifesting within the first four weeks of life. The least severe form is Skin, Eye, and Mouth (SEM) disease, accounting for nearly half of all cases. This localized infection presents with characteristic fluid-filled blisters on the skin, around the eyes, or in the mouth. While SEM has a low mortality rate, it can lead to permanent eye damage if untreated.
If the infection progresses beyond the surface, it can involve the Central Nervous System (CNS) or become disseminated. CNS disease, affecting the brain and spinal cord, may cause subtle symptoms like lethargy, fever, irritability, or poor feeding, often appearing in the second week of life. This form carries a significant risk of long-term neurological damage and developmental challenges for survivors.
The most dangerous presentation is disseminated disease, where the virus spreads throughout the body, affecting multiple major organs such as the liver, lungs, and adrenal glands. Disseminated disease is highly fatal, even with aggressive treatment, and requires immediate intervention. Crucially, many newborns with a serious infection may not initially present with distinctive skin blisters. Instead, they show non-specific signs like a sepsis-like illness, breathing difficulty, or seizures, demanding a high index of suspicion from clinicians.
Diagnosis and Treatment Protocols
When neonatal herpes is suspected, immediate, aggressive intervention is mandatory, even before definitive test results are available. Diagnosis is confirmed using laboratory methods such as polymerase chain reaction (PCR) testing, which detects viral DNA. Samples are collected from various sites, including surface swabs of the eyes, mouth, and rectum, as well as blood and cerebrospinal fluid (CSF) obtained via a spinal tap. CSF testing is particularly important for determining if the virus has reached the central nervous system.
The standard treatment is high-dose intravenous (IV) acyclovir, an antiviral medication administered every eight hours. The duration of IV therapy is determined by the disease classification: 14 days for SEM disease and a minimum of 21 days for CNS or disseminated disease. For infants with CNS involvement, a repeat spinal tap is performed near the end of treatment to ensure the CSF is clear of viral DNA before stopping the IV medication. Following the initial IV treatment, surviving infants are typically placed on oral suppressive acyclovir for six months to improve long-term neurodevelopmental outcomes and prevent recurrences.
Prevention Strategies for Expectant Mothers
Prevention focuses on minimizing the newborn’s exposure to the virus during labor and delivery, especially for mothers with a history of genital herpes. Expectant mothers with recurrent genital herpes are advised to begin suppressive antiviral medication, typically acyclovir or valacyclovir, starting at 36 weeks of gestation. This late-term prophylaxis aims to reduce the frequency of recurrent outbreaks and asymptomatic viral shedding at the time of delivery.
The mode of delivery is important for preventing transmission. A Cesarean section is strongly recommended if the mother has active genital lesions or is experiencing prodromal symptoms, such as tingling or pain, at the onset of labor. This surgical delivery bypasses the birth canal, significantly reducing the risk of viral exposure for the baby. Pregnant women who are seronegative for HSV should also be counseled to avoid acquiring a new genital infection late in pregnancy, which carries the highest risk of transmission to the newborn.